Scientists believe they could soon develop a screening test for schizophrenia after discovering changes in the brain that occur at the earliest stages of the illness.

A team from the Institute of Psychiatry in London has used a brain imaging technique to pinpoint substantial changes to brain structure which appear to take place before the onset of psychotic symptoms.

With a suitable schizophrenia screening method, for the first time, preventive psychiatry becomes a realistic possibility

Dr Tonmoy Sharma, Institute of Psychiatry

The discovery could mean brain imaging is one day used to search for tell-tale signs of schizophrenia.

It also raises the possibility that new treatments could be developed to stall progression of the illness.

The study, led by Dr Tonmoy Sharma, involved 68 participants, including 37 people experiencing their first episode of psychosis and a group of healthy volunteers.

Key regions

Magnetic resonance imaging (MRI) scans identified differences in the structure of key regions, such as the temporal lobe, between the healthy volunteers and those experiencing psychosis.

Previous research had established differences in the brain structure of schizophrenics - but only those with more advanced symptoms.

Because of this, it was difficult to identify whether brain changes were due to the ageing process, a result of their illness or the side effects of their medication.

This research underlines the urgent need to act on the government's NHS Plan which prioritised early intervention in the treatment of schizophrenia

Cliff Prior, National Schizophrenia Fellowship

In this study, all the participants had experienced psychosis for only three months or less, and some had never taken antipsychotic drugs before.

Still, the MRI scans showed quite distinct brain changes in key regions, suggesting that by the time someone starts to showed signs of psychotic behaviour, their brains were already structurally different.

Early intervention

It is now recognised that people with schizophrenia have a better chance of recovery if their psychosis is treated at the earliest possible stage.

The government recognised this by prioritising early treatment for psychosis in its NHS plan published in July.

Until now it has been very difficult to distinguish the early stages of schizophrenia from the beginnings of other psychiatric illnesses, or even just normal adolescence.

Dr Sharma said: "In schizophrenia, we have had a romantic notion of intervening before the condition has developed but so far, our instruments for diagnosis have not been good enough to allow us to do so."

"From this study, we can see that characteristic brain differences are present at a very early stage. Brain imaging may become a powerful predictor of future illness.

"In cancer, we've seen that screening people at risk can have a great effect on treatment success.

"With a suitable schizophrenia screening method, for the first time, preventive psychiatry becomes a realistic possibility."

Men and women

Cliff Prior, chief executive of the National Schizophrenia Fellowship, said: "We already know that outcomes are vastly improved when the illness is spotted earlier and quality care and treatment packages offered.

"This new research underlines the urgent need to act on the government's NHS Plan which prioritised early intervention in the treatment of schizophrenia."

Schizophrenia is the most common form of severe mental illness. It affects about one person in a hundred. The illness usually begins in the late teens and early 20s and is characterised by hallucinations, delusions, hearing voices and changes in behaviour.

In a minority of cases sufferers can become violent towards parents and carers or even complete strangers. Men and women are equally affected but the age of onset is usually younger in men.